util : fallback to plain ASCII drawing if locale is not UTF-8

When printing cgroup and sysfs hierarchies, avoid using UTF-8 box drawing
characters if the locale is not UTF-8.

https://bugzilla.redhat.com/show_bug.cgi?id=871153

3 files changed, 35 insertions, 4 deletions

diff --git a/src/shared/cgroup-show.c b/src/shared/cgroup-show.c
index 2ffed8b739..69fe7fc96d 100644
--- a/src/shared/cgroup-show.c
+++ b/src/shared/cgroup-show.c
@@ -88,7 +88,8 @@ static void show_pid_array(int pids[], unsigned n_pids, const char *prefix, unsi
 
                 printf("%s%s %*lu %s\n",
                        prefix,
-                       extra ? "\342\200\243" : ((more || i < n_pids-1) ? "\342\224\234" : "\342\224\224"),
+                       draw_special_char(extra ? DRAW_TRIANGULAR_BULLET :
+                                         ((more || i < n_pids-1) ? DRAW_BOX_VERT_AND_RIGHT : DRAW_BOX_UP_AND_RIGHT)),
                        pid_width,
                        (unsigned long) pids[i],
                        strna(t));
@@ -207,10 +208,11 @@ int show_cgroup_by_path(const char *path, const char *prefix, unsigned n_columns
                 }
 
                 if (last) {
-                        printf("%s\342\224\234 %s\n", prefix, path_get_file_name(last));
+                        printf("%s%s %s\n", prefix, draw_special_char(DRAW_BOX_VERT_AND_RIGHT),
+                                            path_get_file_name(last));
 
                         if (!p1) {
-                                p1 = strappend(prefix, "\342\224\202 ");
+                                p1 = strjoin(prefix, draw_special_char(DRAW_BOX_VERT), " ", NULL);
                                 if (!p1) {
                                         free(k);
                                         r = -ENOMEM;
@@ -232,7 +234,8 @@ int show_cgroup_by_path(const char *path, const char *prefix, unsigned n_columns
                 show_cgroup_one_by_path(path, prefix, n_columns, !!last, kernel_threads);
 
         if (last) {
-                printf("%s\342\224\224 %s\n", prefix, path_get_file_name(last));
+                printf("%s%s %s\n", prefix, draw_special_char(DRAW_BOX_UP_AND_RIGHT),
+                                    path_get_file_name(last));
 
                 if (!p2) {
                         p2 = strappend(prefix, "  ");
diff --git a/src/shared/util.c b/src/shared/util.c
index 3ac67505f0..2a8afae0ec 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -6140,3 +6140,22 @@ bool is_locale_utf8(void) {
 out:
         return (bool)cached_answer;
 }
+
+const char *draw_special_char(DrawSpecialChar ch) {
+        static const char *draw_table[2][_DRAW_SPECIAL_CHAR_MAX] = {
+                /* UTF-8 */ {
+                        [DRAW_BOX_VERT]           = "\342\224\202", /* │ */
+                        [DRAW_BOX_VERT_AND_RIGHT] = "\342\224\234", /* ├ */
+                        [DRAW_BOX_UP_AND_RIGHT]   = "\342\224\224", /* └ */
+                        [DRAW_TRIANGULAR_BULLET]  = "\342\200\243", /* ‣ */
+                },
+                /* ASCII fallback */ {
+                        [DRAW_BOX_VERT] = "|",
+                        [DRAW_BOX_VERT_AND_RIGHT] = "+",
+                        [DRAW_BOX_UP_AND_RIGHT]   = "\\",
+                        [DRAW_TRIANGULAR_BULLET]  = ">",
+                }
+        };
+
+        return draw_table[!is_locale_utf8()][ch];
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index b979b0e89f..e387b1268a 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -600,3 +600,12 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
                  void *arg);
 
 bool is_locale_utf8(void);
+
+typedef enum DrawSpecialChar {
+        DRAW_BOX_VERT,
+        DRAW_BOX_VERT_AND_RIGHT,
+        DRAW_BOX_UP_AND_RIGHT,
+        DRAW_TRIANGULAR_BULLET,
+        _DRAW_SPECIAL_CHAR_MAX
+} DrawSpecialChar;
+const char *draw_special_char(DrawSpecialChar ch);